Proof Marks

If it is stamped on the barrel of an accepted pistol, it is normal in the inspector's opinion. The 63 refers to an inspector--that inspector's number, perhaps being used by several people in his office, was applied to all Mauser products accepted under contract by the German military in the period 1935-1939. Products made at nearby factories not part of Mauser would also have been accepted by inspector 63 because the inspector's inspected items made in a general area. 77 in Poland, 37 near Suhl, 623 (?) in Vienna etc. though maybe not in the 35-39 period.